نتایج جستجو برای: nonlinear mathematical model
تعداد نتایج: 2369969 فیلتر نتایج به سال:
in this thesis, we consider a mathematical model of cancer with completely unknown parameters. we study the stability of critical points which are biologically admissible. then we consider a control on the system and introduce situations at which solutions are attracted to critical points and so the cancer disease has auto healing. the lyapunov stability method is used for estimating the un...
over the past decades a number of approaches have been applied for forecasting mortality. in 1992, a new method for long-run forecast of the level and age pattern of mortality was published by lee and carter. this method was welcomed by many authors so it was extended through a wider class of generalized, parametric and nonlinear model. this model represents one of the most influential recent d...
بررسی وجود و چندگانگی جوابهای معادلات دیفرانسیل به ویژه با شرایط مرزی اغلب بسی دشوار بوده و همراه با گام های ملالت آور می باشد بطوریکه همواره نیاز به پیش شرط هایی می باشد که معادلات دیفرانسیل با شرایط مرزی مورد نظر باید داشته باشد. بنابراین اثبات آنالیزی وجود و چندگانگی جوابهای مسائل مقدار مرزی غیر خطی اغلب غیر ممکن می باشد. روشهای تقریبی- تحلیلی یا روشهای عددی صرفاً برای بدست آوردن جواب موجود ...
in this paper, we explore a nonlinear mathematical model to study the spread of asthma due to inhaled pollutants from industry as well as tobacco smoke from smokers in a variable size population. the model is analyzed using stability theory of differential equations and computer simulation. it is shown that with an increase in the level of air pollutants concentration, the asthmatic (diseased) ...
in this work the mathematical model of a spatial pattern inchemical and biological systems is investigated numerically. theproposed model considered as a nonlinear reaction-diffusionequation. a computational approach based on finite difference andrbf-collocation methods is conducted to solve the equation withrespect to the appropriate initial and boundary conditions. theability and robustness o...
some considerable damage to steel structures during the hyogo-ken nanbu earthquake occurred. among them, many exposed-type column bases failed in several consistent patterns, such as brittle base plate fracture, excessive bolt elongation, unexpected early bolt failure, and inferior construction work, etc. the lessons from these phenomena led to the need for improved understanding of column base...
In this paper, a generalized mathematical model of spread of infectious disease as SIRS epidemic model is considered as a nonlinear system of differential equation. We prove that for positive initial conditions the resulting equivalence system has positive solution and under some hypothesis, this system with initial positive condition, has a positive $T$-periodic solution which is globally asym...
this paper presents a mathematical model for the vibration analysis of a three-component piezoelectric force sensor. the cubic theory of weakly nonlinear electroelasticity is applied to the model for describing the electromechanical coupling effect in the piezoelectric sensing elements which operate in thickness-shear and thickness-stretch vibration modes. hamilton's principle is used to d...
this paper considers a class of one-dimensional solidification problem in which kinetic undercooling is incorporated into the temperature condition at the interface. a model problem with nonlinear kinetic law is considered. the main result is an existence theorem. the mathematical effects of the kinetic term are discussed
a semi-empirical mathematical model for predicting physical part of ignition delay period in the combustion of direct - injection diesel engines with swirl is developed . this model based on a single droplet evaporation model . the governing equations , namely , equations of droplet motion , heat and mass transfer were solved simultaneously using a rung-kutta step by step unmerical method . the...
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